Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference
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Conf Proc IEEE Eng Med Biol Soc · Jan 2013
An algorithm to improve the estimation accuracy of a non-invasive method for cardiac output measurement based on prolonged expiration.
Cardiac output (CO) monitoring is important in the hemodynamic management of critically ill patients. In a previous study, a novel non-invasive technique for CO monitoring based on prolonged expiration was proposed. The novel method showed good agreement with thermodilution on stable mechanically ventilated patients; unstable patients were excluded. ⋯ This prospective study has been carried out on three cardiac surgery patients; eighteen CO measurements were performed on each patient, and these values were compared with data obtained by thermodilution. The designed and tested algorithm allowed to reach a good agreement between CO measured by our method and by thermodilution (e.g., the mean percentage differences were 4%, 11% and 3%). Even though further validation is necessary, the results are quite promising and the adopted solution appears to allow the suitability of the prolonged expiration method also on unstable patients.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2013
Preprocessing by means of subspace projections for continuous Cerebral Autoregulation assessment using NIRS.
Cerebral Autoregulation (CA) refers to the capability of the brain to maintain a more or less stable cerebral blood flow (CBF), despite the changes in blood perfusion. Monitoring this mechanism is of vital importance, especially in neonates, in order to prevent damage due to ischemia or hemorrhage. In clinical practice near-infrared spectroscopy (NIRS) measurements are used as a surrogate measurement for CBF. ⋯ Obtained results indicate that the proposed method reduces the effect of discontinuities between consecutive segments. In addition, this methodology is able to subtract the influence of SaO2 from NIRS measurements. This approach facilitates the introduction of NIRS for online CA assessment.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2013
Peristaltic hemodynamics of a new pediatric circulatory assist system for Fontan circulation using shape memory alloy fibers.
Fontan procedure is one of the common surgical treatments of congenital heart diseases. Patients with Fontan circulation have single ventricle in the systemic circulation with the total cavopulmonary connection. We have been developing a pulmonary circulatory assist device using shape memory alloy fibers for Fontan circulation with total cavopulmonary connection. ⋯ Then, we developed a sequential contraction controller for the assist system, which could reproduce the wall contractile velocity at 6.0 to 20.0 cm/sec. We examined hemodynamic characteristic of its function using a mock circulatory system, which consisted of two overflow tanks representing venous and pulmonary arterial pressures in Fontan circulation. As a result, the pulmonary circulation assist device with sequential contraction could achieve effective promotion of the pulsatility in pulmonary arterial flow.
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Conf Proc IEEE Eng Med Biol Soc · Jan 2013
Hypnosis control based on the minimum concentration of anesthetic drug for maintaining appropriate hypnosis.
This paper proposes a novel hypnosis control method using Auditory Evoked Potential Index (aepEX) as a hypnosis index. In order to avoid side effects of an anesthetic drug, it is desirable to reduce the amount of an anesthetic drug during surgery. For this purpose many studies of hypnosis control systems have been done. ⋯ The minimum effect-site concentration is estimated utilizing the property of aepEX pharmacodynamics. The infusion rate of propofol is adjusted so that effect-site concentration of propofol may be kept near and always above the minimum effect-site concentration. Simulation results of hypnosis control using the proposed method show that the minimum concentration can be estimated appropriately and that the proposed control method can maintain hypnosis adequately and reduce the total infusion amount of propofol.
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An ultra-low-cost pulse oximeter is presented that interfaces a conventional clinical finger sensor with a mobile phone through the headset jack audio interface. All signal processing is performed using the audio subsystem of the phone. In a preliminary volunteer study in a hypoxia chamber, we compared the oxygen saturation obtained with the audio pulse oximeter against a commercially available (and FDA approved) reference pulse oximeter (Nonin Xpod). Good agreement was found between the outputs of the two devices.